UMTS : La Convergence des Rseaux Mobiles et dInternet

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Cellular networks evolution from 2G to
3G CEENet 2004 Wireless and Mobile Networking
Budapest (Hungary) August 20th, 2004 Sami
Tabbane
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Summary

• 2G networks architecture
• 2,5G evolution towards third generation
• 3G services and evolution
• Conclusions

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I. 2G networks architecture
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GSM basic network architecture
NSS
BSS
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BTS

• Radio transmission/reception management
  (modulation/demodulation, equalisation,
  interleaving ...)
• Physical layer management (TDMA transmission,
  SFH, coding, ciphering ...)
• Link layer management (LAPDm)
• Received signal quality and power measures.

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BSC

• Radio resource management channel allocation,
  BTS measures processing, BTS and MS power
  control, handover ...
• Interfaces management with the MSC (gathers the
  traffic towards the MSC) and with the BTSs.

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MSC

• Management of the communications between the
  mobiles and the fixed network.
• Handover management.
• Interconnection with the
• fixed network (switching features).
• Management of the visiting
• users with the VLR.
• GMSC function (Gateway
• MSC) gateway for the calls
• coming/going towards an external network.

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HLR/VLR

• HLR (Home Location Register)
• Subscribers database
• - Subscription data IMSI, MSISDN, subscription
  type (restrictions, supplementary services, ...)
• - Location information mobile VLR number.
• VLR (Visitor Location Register)
• Data IMSI, MSISDN, TMSI, MSRN, subscription
  type, location area, ...

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Suscriber Identity Module

• Informations subscriber identity, password
  (PIN), subscription informations (authorized
  networks, call restrictions, ), security
  algorithms, short numbers, last received/dialled
  numbers, last visited location area, ...
• SIM card GSM terminal access to GSM services.

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GSM services characterization

• GSM circuit switched-based technology.
• 2 types of services (ISDN based classification)
• ? Bearer services Telecommunications services
  offering transmission capabilities (bitrate, BER,
  synchronous/asynchronous mode ...) between
  network access points.
• ? Teleservices Telecommunications services
  offering capacities taking into account the
  terminal equipment (telephone, SMS, ...).

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Some GSM bearer services
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GSM teleservices

• Radiotelephone. ? Emergency calls.
• Short message service.
• Fax. ? ...
• - Supplementary services
• Calling number identification. ? Call waiting,
• Call transfer (on non reply, unconditional, on
  busy, ...)
• Conference call, ? Closed user group ...

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II. 2,5 G evolution towards 3G
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High Speed Circuit Switched Data (HSCSD)

• Objective High bitrates radio bearers.
• Introduced in phase 2 (1997).
• Use several time slots per mobile (up to 6).
• Bitrates 19.2  28.8  28.4  48  56 and 64
  kb/s.
• Asymetric configurations (n slots on the uplink
  and m slots on the downlink).
• Problem Circuit-switched (cost capacity).

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Customized Applications for Mobile network
Enhanced Logic (CAMEL)

• Intelligent network concept
• CAMEL defines an architecture and mechanisms
  based on IN.
• Separation
• -1- Applications and Services specific features
  (SCP Computers for services provision SMP
  Management point for data of one or several
  SCPs),
• -2- Applications comon processing (SSP Switch
  for service access)
• Objective Allow roaming subscribers to use their
  services even though these are specific to their
  operator.

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CAMEL services introduction
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SIM Toolkit

• ? Principle The SIM card can initiate actions on
  the terminal.
• ? Objectives Allow exchanges between the network
  and the SIM through SMSs (without displaying
  them)
• Value-added services provision.
• ? Examples
• - Reservation in a restaurant (send a menu by
  the network, manages user choices and the SIM
  card sends back the reservation in an SMS).
• - Menus management (kiosk services ).

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General Packet Radio Service 2,5 G
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Introduction of packet-switching

• Packet switching advantages
• Transmission of non-periodic and bursty data
  (e.g. mails),
• Frequent small packets (e.g. telematic, billing
  and micro-payments),
• Large but unfrequent packets (e.g. ftp).

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GPRS principles

• ? Higher bit-rates per TCH (9.05  13.4  15.6 
  21.4 kb/s),
• ? Higher bit-rates with up to 8 time slots per
  user,
• ? Channel sharing by active terminals,
• ? Separate allocation of uplink and downlink
  channels,
• Separate packet transmission network between the
  BSC and external packet transmission networks
  GSS (based on SGSN and GGSN).

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GGSN (Gateway GPRS Support Node) Functions

• Routing IP router which supports dynamic or
  static routing,
• Security Ciphers the communications towards or
  from the mobiles.
• Mobility management Use of routing areas.
  Handover management between the BSCs and other
  SGSNs.
• Authentication At Attach and inter-SGSN RA
  updates.
• Sessions management At each session, the SGSN
  activates a PDP (Packet Data Protocol) context.
• Billing Production of the CDRs according to the
  quantity of information and the session duration
  (attachment, duration of active PDP context).
• SMS Supports the Gd interface for the
  communications with the SMS-GMSC and the
  SMS-IWMSC.

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GGSN (Gateway GPRS Support Node) functions

• Routing IP router which supports dynamic or
  static routing,
• Security Includes firewalls for filtering the
  packets coming from external IP networks.
• Gateway Allows the connection to other IP or
  GPRS networks.
• Mobility management Allows the routing of the
  packets towards the users SGSNs, according to
  their mobility.
• Sessions management At each session, the GGSN
  allocates an IP address to the mobile.
• Billing Production of the CDRs according to the
  quantity of information and the session duration
  (attachment, duration of active PDP context).

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GPRS introduction in a GSM network
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GSM to GPRS Evolution
? BSS Evolution -  Replace/Upgrade existing
elements BTS, BSC, OM, Network planning, Links
(Abis, Ater, ). -  New element PCU (Packet
Controller Unit). ? NSS Evolution - A new
core network (GSS) dedicated to GPRS IP/ATM
based, network packet nodes (SGSN, GGSN),
Internet equipment (DNS servers, Firewalls, ).
-  Evolution of the network elements HLR,
MSC/VLR, SS7.
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Main characteristics

• ? Same physical layer as GSM.
• Service separated from GSM Different fixed
  networks (new network entities and new
  protocols).
• New mobiles, 3 types
• - A GSM and GPRS at the same time,
• - B GSM or GPRS ( dual mode  in idle
  mode),
• - C GSM or GPRS a priori.

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Services classification
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Enhanced Data rates for the GSM Evolution 3G
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Enhanced Data rates for GSM Evolution (EDGE)

• Objective
• Increase the data bitrates (GPRS ? EGPRS).
• Bitrates
• - 473 kb/s for the terminals of 100 km/h
  maximum.
• - 80-130 kb/s on average.
• - 144 kb/s for the terminals of 250 km/h
  maximum.
• Means
• -1- New modulation (8-PSK).
• -2- Link adaptation.
• New mobiles, upgrade/replacement of TRXs and
  capacity enhancement (Abis, ).

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EDGE introduction
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III. 3G services and evolution
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Internet and GSM
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Motivations for a new system

• ? Convergence computer, telecommunications and
  audio applications.
• ? Present services Mainly voice (gt 70 of
  cellular operators revenues).
• ? Extend to data and combination of voice/data.
• ? New frequency bands (WARC 92).
• ? Migration (operators and providers) towards
  more diverse and developed applications and
  services.
• ? Technological progress (networks, systems, DSP,
  )
• ? Definition and development of new systems.

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Development initial planning
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UMTS main features (1)

• ? Integration of existing mobile services
  (cellular, cordless, paging, PMR, ) and
  introduction of service portability (Virtual Home
  Environment, ).
• ? Choice among various terminals and service
  providers.
• ? Flexible terminals supporting several radio
  interfaces (software radio).
• ? Global roaming for terminals and services.

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UMTS main features (2)

• ? Voice quality similar to that of fixed
  networks.
• ? Satellites services for areas non covered by
  terrestrial BTS.
• ? UMTS frequency spectrum 1885-2025 MHz and
  2110-2200 MHz.
• ? Security and anti-fraud techniques against
  access to data by non-authorized persons or
  entities.

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UMTS main features (3)
? Wideband multimedia mobile services ? 2 Mb/s
for indoor, reduced mobility (10 km/h), ? 384
kb/s for urban outdoor (120 km/h), ? 144 kb/s for
rural outdoor, important mobility (500 km/h). ?
Variable quality of service (BER between 10-3 and
10-6, delays between 30 and 300 ms). ? Asymetric
and variable bitrate transmission. ? Multiples
services per user ? Speech 8 kb/s, ? Data
2,4 at 6x64 384 kb/s, ? Video 384 kb/s, ?
Multimedia.
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Objectives and Features (1)
? Wideband. ? Service integration. ? Packet
access. ? Techniques for capacity enhancement
multi-user detection, interference cancellation,
adaptive antennas, MIMO, ? Inter-system (GSM
3G) and inter-frequencies (hierarchical networks)
handover.
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Objectives and Features (2)

• Main challenge Merge mobile phone radio
  coverage to Internet and other multimedia
  applications.
• ? 3G systems must provide
• Flexible multimedia services management,
•   Internet access,
• Flexible services support,
• Packet access at an interesting cost for  Best
  Effort  services.
• Most of multimedia applications accessible
  through Internet
• ? 3G access Mobile Internet.

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Introduction of UMTS
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3G environment and multi-mode terminals (UMTS
Forum)
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Evolution from 2,5G to 3G networks
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UMTS R99 main features
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UMTS R4 Features
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UMTS R99/R4 and GSM/GPRS
IP/ATM Core Network(s)
Core Network
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UMTS R5 Features
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Introduction of IMS
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UMTS R6 Features
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Roadmap to All-IP Networks - 3GPP R6

PS IM Domain All-IP
IP in UTRAN
IPv4 IPv6 Networks
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UMTS features and sub-systems for service
provision
Introduction of IP
Development of multimedia IP services with
hardware and software componants integration
IMS IP Multimedia Service
Customization
User framework portability
VHE Virtual Home Environment
Provision by third parties
Services development by external applications and
contents providers
OSA Open Service Access
Terminal related
Adaptation of the service to the user terminal
according to its characteristics, task sharing
with the network
MeXE Mobile eXecution Environment
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IMS - IP Multimedia Service

• QoS characteristics differentiation for voice or
  video associated with a multimedia session
  (streaming, IM, etc.)
• Separation of the planes IP data and session
  control (SIP)
• Independant from the access network

Principles
IMS for mobile networks GPRS, EDGE, UMTS
CDMA2000Non real time services IP multimedia
applications plate-form IETF specifications based
IMS extended to wideband fixed networks (xDSL,
WLAN, cable, ) Supports services convergence on
fixed and mobile networks (conversion CS voice
traffic in IP)
R5
R6

• Introduction of multimedia services with QoS
  management
• Integration with other networks (WLANs, fixed,
  CDMA2000, )
• Flexible billing billing / service,
  connectivity, QoS, time, destination

Advantages

• Implementation of many equipments, softwares,
  interfaces, protocols, which may cause
  integration, interworking and optimisation
  problems
• Ex. S-CSCF (Call Status Control Function) SIP
  AS (SIP Application Server) OSA SCS (Service
  Capability Server) IM-SSF (Inter-working
  Module) CSE (Camel Service Environment) HSS
  (Home Subscriber Server)
• Security and QoS with Internet interconnection

Drawbacks
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Componants and interactions between IMS and other
networks
IMS
Application Servers (SIP, OSA, CAMEL)
Session Control
Media Control
RAN
ISUP
SIP
PSTN
RNC
PCM
Media Gateway
Media Gateway
User Data
SIP
Packetnetwork
AMR
Packet Support Node
Backbone IP
Packet Gateway
Core packet
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VHE - Virtual Home Environment

• PSE (Personal Service Environment) portability
  between networks and terminals user services
  interaction modes, multiple subscriptions
  management (pro/perso), multiple terminals and
  preferences according to the location.
• Same features always available to the user
  interface and services customization, whatever
  the network and the terminal.
• Independancy relatively to the network (roaming)
  and the terminal

Principles
Applications
VAB Virtual Address Book
Customer Care service
Calender multiparty application
Multimedia Delivery service
Use of many types of terminals to access and
update user data
Support to the users interactive tutorials,
problems detection and solutions proposal,
on-line assistance,
Coordinated calendar management among remote
users answers collection, meeting dates
determination,
Adaptation of the video to the user terminal
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OSA - Open Service Access

• Introduction of SCF (Service Capability
  Features) to provide applications with service
  features call control, user location,
• Access to network features which application
  developpers will use to develop or improve
  services

Principles
VPN, teleconferencing, LBS Applications
implemented in one or many application servers
Applications
Advantages

• Introduction of services by third parties
  through standardized interfaces and applications
• Easier introduction of application and service
  providers

• Supervision of the services and contents by the
  operator
• QoS management by external providers for offered
  services

Drawbacks
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MExE - Mobile Execution Environment

• Standardised execution environment for the
  mobiles
• Negociation of the features between UE and MExE
  server during service initiation or dynamically
• Execution of service applications inside the UE
  or in the MExE server
• MExE defines the classmarks to support various
  terminals (Classmark 1 WAP environment,
  Classmark 2 PersonalJava, Classmark 3 J2ME CLDC
  MIDP environment )

Principles

• Adaptation of the services to user terminals

Advantages

• Définition, standardisation and implementation
  of these terminal classes

Drawbacks
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USIM characteristics
Capacities

• 64K, 128K, eventually 1Mo

• Operator and user profiles management through
  radio interface (OTA, Over The Air) VAS
  real-time implementation, with updates and
  applets downloading, file management,

Profile management
Security

• Point-to-point messages exchange security
  provision in OTA

• Pro-active SIM card for execution of features
  management of UE by USIM and thus by the operator

SIM ApplicationToolkit (STK)

• OTA based on SMS transport, then via other
  bearers (CSD, GPRS, UMTS)

Operations
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Interactions for service provision in UMTS
Multimedia IP servers
IMS
QoS management
RAN (CAC, LC)
Application servers BDD user profiles (PSE,
VHE, )
OSA
Application and Content providers
USAT, MeXE, OTA, CAMEL, LCS,
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Services evolution in UMTS R99/R4/R5/R6 networks
Evolution of the services (voice and
interpersonal services)
Voice/Videotelephony IM/Presence Messaging RCS LCS
GTT
Voice/Videotelephony Instant
Messaging/Presence Rich Call
Services Messaging
Voice Messaging Videotelephony
Voice SMS/MMS
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QoS and planning problems in UMTS
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QoS problems in UMTS
QoS guaranteed in CS but not in IP QoS problems
similar in UMTS as in any IP network
QoS provision in IP ?

• Necessary definition of end-to-end QoS management
  functions
• No 3GPP specifications for QoS in PS and in IMS
• Implementation choice depends on the operator
  preferences, the network, the service model,
  equipment providers,
• Resources negociated between operators through
  DiffServ, DSCP at network borders

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QoS provision in UMTS

• RSVP, overprovisionning, DiffServ/ IntServ, MPLS
• In R5, definition of 5 signalling scenarios for
  end-to-end QoS
• 3 with PDP/DiffServ interworking,
• 2 with RSVP signalling

Core network
Radio access
CAC - Call Admission Control
Load/Congestion Control

• RNC admits or rejects new users or new RAB
  (Radio Access Bearers) according to network load,
  users priorities and resource availability
• Used at network UE access RAB reconfiguration or
  allocation and HO according to the events
• UL channel interference and DL power related

• RNC supervises, detects and manages congestion
  situations during users connection
• Load reduction via queueing mechanisms,, by
  delaying the packets of the best effort traffic
• Mechanisms not standardised, designed by the
  equipment vendors and optimised by the operators
• Principles CAC based on the interference level,
  on the admission politics/load factor, etc.

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Cell breathing phenomena
Radio phenomena
Case 2 10 users
Case 1 20 users
cells
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Capacity, cell radius and noise rise
Cell load 20 of the maximum capacity
Interference level y dB
R and R are the cell radius in the 2
load situations
Cell load 50 of the maximum capacity
Interference level y 2 dB
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WCDMA systems and planning

• Interaction between coverage and capacity
  (estimation of interference level, relation
  between user number and cells bitrates),
• Multi-services aspect (differents services with
  different Eb/N0),
• Power control (minimum transmission power of the
  MSs and BTSs, difference between UL and DL),
• Rake receiver and Soft HO.

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Conclusions

• UMTS introduces
• ? an environment to develop and provide services
  wideband, flexible, customized, accessible from
  outside, open on Internet, with Internet and
  computer-related technologies.
• Richer and wideband services
• But
• More complexity (design, planning, integration,
  deployment, security, optimisation, operation).